Zero insertion force (ZIF) connectors are employed to reduce or eliminate the forces that would otherwise be imposed on a plug, cable or other electrical conductor as the conductor is being inserted into a connector. The elimination or reduction of these insertion forces is particularly essential for components having small contacts and/or conductive strips which could easily be damaged by forces encountered when making an electrical connection. ZIF connectors provide open channels which enable the fragile conductors to be placed substantially adjacent the contacts. The contacts and/or the conductors then are moved relative to one another to achieve the necessary electrical connection.
Many electronic devices employ flat flexible cables having a plurality of electrically conductive strips disposed in a parallel array. The conductive strips may be formed by thin wires, or an electrically conductive ink. The electrically conductive strips typically are covered by plastic to provide physical protection and electrical insulation. In certain embodiments, the electrically conductive strips may be disposed on both sides of a central plastic support and then are covered by outer plastic layers. In the typical situation a portion of the protective and insulating plastic is removed adjacent one or both ends of the cable to facilitate electrical connection. Many flat flexible cables are very thin (e.g. 0.004 inch to 0.014 inch) and therefore can be damaged easily when making an electrical connection. As a result, ZIF connectors often are employed with flat flexible cables.
The prior art ZIF connector for flat flexible cables typically has included flexible contacts and an actuator to physically abut and move each contact. One general type of prior art ZIF connector includes contacts having a pre-load alignment or bias that permits the unobstructed entrance of the flat flexible cable into its fully seated position. The actuator of this type of prior art ZIF connector then is moved to physically urge the contacts against the conductors of the flat flexible cable. One particularly effective version of this general type of ZIF connector is shown in U.S. Pat. No. 3,989,336 which issued to Rizzio, Jr., and Janzow on Nov. 2, 1976 and is assigned to the assignee of the subject application. Other ZIF connectors of this general type are shown in U.S. Pat. No. 3,090,028 which issued to Hall et al on May 14, 1963 and U.S. Pat. No. 3,149,896 which issued to Hall on Sept. 22, 1964.
Another type of prior art ZIF connector includes a contact which is pre-loaded into a position to engage a flat flexible cable. However, this type of ZIF connector includes an actuator that can open the contacts to provide an unobstructed passage for the flat flexible cable to enter. An example of this type of ZIF connector is shown in U.S. Pat. No. 4,449,773 which issued to Esser et al.
U.S. Pat. No. 3,701,071, which issued to Landman on Oct. 24, 1972, shows a ZIF connector where a circuit board is inserted into a hinged member which is rotated to bring one side of the circuit board into engagement with electrical contacts.
Prior art connectors also are available for cables or cards having conductors on two sides. The prior art connectors of this type have included a generally C-shaped contact, the arms of which are spaced from one another a distance greater than the thickness of the cable or card. The cable or card is inserted between the arms of the contacts, and an actuator is moved to urge the contact arms a controlled amount to make electrical connection with the flat cable or card.
U.S. Pat. No. 3,848,952, which issued to Tighe on Nov. 19, 1974, shows a connector having generally C-shaped contacts, with the arms of the "C" being slightly offset from one another. The connector of U.S. Pat. No. 3,848,952 is adapted specifically for a rigid card. The card is inserted into the ZIF contact at an angle and is then rotated to biasingly engage both of the arms of the C-shaped contact. The rigid board is then locked into the required alignment by structural components spaced from the connector.
Most of the above described ZIF connectors, and in particular those having an actuator to move the contacts, are limited to cables having a prespecified thickness. Improper electrical connection may result if a cable of lesser thickness is employed. Conversely, the contacts, the cable or the connector housing may be damaged if a thicker than specified cable is employed.
In view of the above, it is an object of the subject invention to provide a ZIF connector that can accept flat cables of various thicknesses.
It is another object of the subject invention to provide a ZIF connector that can be used with flat cables having conductors on one or both sides.
It is an additional object of the subject invention to provide a ZIF connector that enables positive connection with a flat cable without urging the contacts toward the flat cable.
A further object of the subject invention is to provide a ZIF connector which effectively prevents damage to the contacts.